Apparatus for compacting material

ABSTRACT

An improved apparatus for applying a relatively uniformly distributed pressure to a quantity of compactible material, such as a ferrous metal powder, is described. The apparatus includes an essentially self-contained isostatic system within a pressure vessel, and there is no requirement for injection of a high pressure fluid into the pressure vessel from an external source. A deformable mold means is suspended within the pressure vessel by a support means arranged to be free to move for a limited distance within the pressure vessel during a pressurization of the chamber within the vessel. The apparatus includes means for filling the deformable mold means with the compactible material together with means for closing the chamber of the pressure vessel in which the deformable mold means is inserted so as to allow a relatively high compacting pressure to be applied to the material without producing unwanted stresses or design variation in the final product to be produced.

United States Patent 1191 Baxendale et al.

[451 Aug. 20, 1974 APPARATUS FOR COMPACTING MATERIAL [75] Inventors: Kenneth C. Baxendale, Macedon; Werner E. Bergemann, Brighton: David B. Camp, lrondequoit; John L. Evershed, Webster; Mason M. Howlett, Penfield; Robert A. Waasdorp, Fairport, all of NY.

[73] Assignee: The Gleason Works, Rochester,

[22] Filed: Jan. 5, 1973 [21] Appl. No.: 321,438

[52] US. Cl. 425/78, 425/405 'H [51] Int. Cl..... B30b 5/02, 83% 15/16, B30b 11/00 [58] Field of Search 425/409 H, 78

[56] References Cited UNITED STATES PATENTS 2,648,125 8/1953 McKenna et a1. 425/405 H X 3,044,113 7/1962 Gerard ct a1 425/405 H X 3,093,862 6/1963 Gerard et a1 425/405 H X 3,118,177 1/1964 Van Platen 425/405 H X 3,123,862 3/1964 Levy 425/405 H X 3,193,900 7/1965 Wendt 425/405 H 3,593,373 7/1971 Loomis 425/405 H X Primary Examiner-J. Howard Flint, Jr. Attorney, Agent, or FirmRalph E. Harper ABSTRACT An improved apparatus for applying a relatively uniformly distributed pressure to a quantity of compactible material, such as a ferrous metal powder, is described. The apparatus includes an essentially selfcontained isostatic system within a pressure vessel, and there is no requirement for injection of a high pressure fluid into the pressure vessel from an external source. A deformable mold means is suspended within the pressure vessel by a support means arranged to be free to move for a limited distance within the pressure vessel during a pressurization of the chamber within the vessel. The apparatus includes means for filling the deformable mold means with the compactible material together with means for closing the chamber of the pressure vessel in which the deformable mold means is inserted so as to allow a relatively high compacting pressure to be applied to the material without producing unwanted stresses or design variation in the final product to be produced.

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APPARATUS FOR COMPACTING MATERIAL RELATED APPLICATION This application is related to subject matter described in a US. application, Ser. No. 321,437, entitled Tooling for Receiving and Supporting a Quantity of Powder Material to be Pressed into a Self-Supporting Compact, filed even date herewith in the name of Kenneth Baxendale.

BACKGROUND AND BRIEF DESCRIPTION OF INVENTION It is known in the art to apply a force to a powder ma terial by placing a quantity of the powder material in a deformable mold and then subjecting some or all of the external surfaces of the mold to a relatively high pressure. Such a compacting procedure is typically referred to as isostatic compacting because, in theory at least, there is an equal application of pressure to all sides of the quantity of material, and this results in a uniform compaction and increase in density of the material. One form of isostatic compaction involves the loading of a powder material into an elastomeric bag or other deformable mold at a point outside of a pressure vessel, followed by an immersion of the loaded bag into a liquid system supplied to a chamber within the pressure vessel. This type of isostatic compacting is more generally referred to as wet bag compacting, and its provision for complete immersion of the compactible mterial in a liquid bath which is pressurized results in a true isostatic compaction of the material.

A modified form of isostatic copaction involves the loading of a bag, or deformable mold, with a powder material while the bag is positioned within a chamber of a pressure vessel. After loading, the bag is plugged, the pressure vessel is closed, and a fluid pressure force is applied to certain of the external surfaces of the bag so as to compact the powder material contained therein. This technique is referred to as dry bag compacting and is usually described as a form of isostatic compacting even though a part of the external surface area of the deformable mold is not subjected to direct pressure from the fluid system operating in the pressure vessel. However, substantially theoretical isostatic compacting is achieved because indirect forces are applied to all unexposed surfaces of the mold so 'as to provide for a substantially simultaneous and equal pressure from every direction. The just described dry bag technique offers an advantage of increased production capability by the fact that the deformable mold is filled with powder material and later unloaded without any required movement of the mold itself from the confines of the pressure vessel.

A further form of modified isostatic compaction involves a simulation of a fluid system through the use of relatively soft or flowable substances, such as certain elastomeric materials, which are placed around the quantity of material to be compacted (or a deformable mold in which the material is contained), and the relatively soft substances impart substantially uniform pressure to all sides of the material being compacted when mechanical forces are applied to the soft substances. Generally, this technique is described as a dry bag technique when a deformable mold is filled in place in a pressure vessel.

The present invention is mainly concerned with improvements in dry bag techniques for isostatic compaction, although the principles of the invention can be applied equally well to situations where the deformable mold is initally filled while positioned externally of a pressure vessel.

One of the problems of prior art compacting techniques is the problem of obtaining uniform characteristics in a final product being produced by a rapid production technique. This is especially true in the case of ferrous metal powder compaction which requires relatively high compacting pressures on the order of 40,000 to 50,000 psig, or even higher pressures, to obtain coherencey and requisite density of the compacted part. It is very difficult to control the placement of a deformable mold in a pressure vessel and to avoid unwanted applications of stresses to a quantity of material contained therein during rapid pressurization and depressurization of the chamber to and from such relatively high pressures. It is known, for example, that the walls of the pressure vessel chamber, and the closure members which seal the chamber, actually deflect by measurable amounts during a very high pressurization of the chamber despite the use of strong and sometimes relatively complex structures for resisting or compensating for such deflections. Various attempts have been made to improve the integrity of equipment used for carrying out isostatic compaction at relatively high pressures, but many of these attempts have worked at odds with the needs of a high production system which provides easy access to a chamber for loading and unloading at a relatively rapid production rate. For example, screw or breach type closure members have been used for sealing compacting chambers, but such members require a time consuming operation to insert and remove them relative to a pressure vessel. On the other hand, attempts to use simpler closure members have resulted in problems in controlling unwanted distortions in the deformable mold and in providing for a rapid pressurization and depressurization of the compacting zone within the pressure vessel.

The present invention offers improvements in this relatively highly developed art by providing for an apparatus which can be used on a sustained basis for relatively rapid production of compacted parts. A particular use of the apparatus of this invention permits rapid production of ferrous metal preforms which can be subjected to subsequent heating and forming treatments which produce high strength, precision parts having nearly per cent theoretical density in their final form. It has been found that the successful productionof such precision parts requires a careful control of characteristics of the intermediate compacted part which is produced by the apparatus to be discussed herein.

In accordance with the present invention, an improved compacting apparatus is provided with an essentially self-contained isostatic system within a pressure vessel so that there is no requirement there is no requirement for injecting a high pressure fluid into the pressure vessel from an external source. By providing a self-contained isostatic system, certain unusual fluids and semi-liquid materials can be used which are not usable in systemsrequiring a pumping and delivery of the isostatic fluid from an external source. For example, certain high viscosity silicone fluids and other polymer type fluids may be used with the apparatus of this invention. The self-contained isostatic system is pressurized by an intensifier means operating through a closing means for the pressure vessel, and pressurization of the isostatic system within the pressure vessel causes the closing means to move outwardly from the pressure vessel to engage a pressure plate means while maintaining a sealed relationship between the closing means and the pressure vessel.

In a specific embodiment of the invention, a pressure vessel is provided with closing means at opposite ends of a bore formed therethrough, and the closing means are arranged so that the pressure vessel can be loaded, pressurized, depressurized, and unloaded without disengaging high pressure seals for either end of the bore. Further, the closing means are designed to expand outwardly in opposite directions away from the pressurized inner chamber of the pressure vessel during a compacting operation so a to engage a pair of spaced pressure plates which are designed to resist the relatively high pressure developed in the pressure vessel. One or more pressure vessels can be carried in a support structure for rapid, successive movement between the spaced pressure plates to provide for a pressurization of each vessel after being loaded with a quantity of compactible material. After pressurization and subsequent depressurization, each pressure vessel is moved, in turn, away from the spaced pressure plates so that the compacted material can be removed and a new quantity of material introduced into each pressure vessel.

In accordance with another feature of the present invention, the improved compacting apparatus is provided with a support means for suspending a deformable mold means in a chamber of a pressure vessel so that a quantity of material to be compacted can be subjected to substantially equal forces from all directions during a complete pressurizing and depressurizing cycle. The support means is mounted within the chamber so as to be free to move for a limited distance, along an axis passing through the chamber, in response to changing pressure conditions within the chamber. This movement allows the suspended deformable mold means to follow distortions of a closing means associated with the pressure vessel without applying unwanted stresses to the material being compacted within the deformable mold means. This arrangement permits a controlled pressurization of the deformable mold means without the chamber response to such pressurization being imparted to the material being contacted. In this sense, the specific arrangements of the invention provide for a better balancing and more uniform application of forces to a quantity of material in an isostatic technique which lends itself to very high production rates.

A further feature of the invention is a provision'for application of a force to a deformable mold means contained within the pressure vessel with a system which permits full control of rapid pressurizing and depressurizing cycles which do not impart unwanted loads or shocks to the material being compacted.

The overall arrangement of the present invention is one which includes on or more pressure vessels which can be sequentially moved into position for carrying out rapid compacting operations and which include relatively simple and reliable driving arrangements for such movements. For example, a pair of pressure vessels can be mounted to pivot about a common axis, and

a full cycle of closing, compacting, and depressurizing can be carried out without further movement or adjustment of position of the relatively large and heavy pressure vessel from its compacting position. Upon completion of the compacting operation, the pressure vessel can be rapidly rotated to a loading/unloading position while the second vessel of the pair is advanced to the compacting position.

IN the context of the present specification reference will be made to certain terms and phrases which are generally used and understood by persons skilled in this art. For example, reference will be made to compactible materials, and this is meant to include any material which can be pressed to a new shape or to an increased density by an application of force thereto. This includes loose material, usually in the form of a powder, and the powder can include various known metal, synthetic plastic, ceramic, and cermetmaterials, and the like. Also, this term includes material which has been previously compacted and which can be further compacted to an increased density and new size or shape. Reference will also be made to deformable mold means, and this is meant to include eleastomeric bag or diaphragm structures designed to contain a material during compaction. Such structures can be made from various forms of polyurethane, and other elastomeric materials which offer characteristics of resilience, deformability, and recoverability of shape and size after being deformed. The use of the term isostatic herein is intended to include the various types of true and modified isostatic compaction discussed at the beginning portion of this specification.

These and other features and definitions of the present invention will become apparent in the more detailed discussion which follows. In that discussion reference will be made to the accompanying drawings, as briefly described below.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an elevational view of the overall apparatus of the present invention together with certain collateral equipment used for dispensing powder into the apparatus and for removing compacted parts therefrom;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1 and illustrating a driving means for controlling movement of a pair of pressure vessels associated with the apparatus;

FIG. 3 is a diagrammatic elevational view, in cross section, showing essential details of the pressure vessel and its contained structures in accordance with the present invention;

FIG. 4 is an exploded isometric view showing an isostatic tooling assembly which may be used with the apparatus of this invention;

FIG. 5 is an elevational view, partly in section, of a pressurizing means which applies a force to a selfcontained isostatic system contained within the pressure vessel of the present invention;

FIG. 6 is a circuit diagram illustrating hydraulic control functions for pressurizing and depressurizing a pressure vessel in accordance with the present invention; and

FIG. 7 is a circuit diagram showing hydraulic control functions for a driving means associated with movement of a pair of pressure vessels into and out of a compacting station.

DETAILED DESCRIPTION OF INVENTION FIGS. 1 and 2 illustrate a specific embodiment of the present invention which includes two separate pressure vessels l0 and 12 carried at opposite ends of a support structure 14 so that the two pressure vessels can be rotated about a common axis 16 to provide for altemating placement of each pressure vessel in a compacting station defined between a pair of pressure plate means comprising two relatively thick metal plates 18 and 20 mounted on a base structure 21. The pair of pressure plate means 18 and 20 are rigidly secured in a parallel, spaced relationship to each other by securing devices associated with three support posts 22 which pass through openings formed in each of the pressure plates. As shown in FIG. 2, the three posts 22 are arranged in a triangular configuration so as to minimize stresses which will be applied to the two pressure plate means 18 and 20 supported thereby.

With the configuration shown in FIGS. 1 and 2, each of the pressure vessels and 12 is alternately loaded and unloaded at the postion shown for the pressure vessel 12 exteriorly of the compacting frame. Loading of a compactible material, such equipment 24 which provides for a dispensing of measured quantities of powder into a mold cavity provide in each pressure vessel. Unloading is carried out with an extractor means 26 which functions to engage a compacted part and to withdraw the compacted part from the mold cavity of the pressure vessel. The loading and unloading devices may be arranged as shown in FIG. 2 so as to be alternately pivoted into position over the mold cavity of a given pressure vessel in accordance with whatever operation is to be performed. A two way hydraulic ram means 28 may be controlled to advance and retract the loading and unloading devices 24 and 26 about a pivot axis 30 which is arranged to bring one or the other of the devices into alignment with the mold cavity of the pressure vessel being loaded or unloaded.

After a given pressure vessel is loaded with compactible material, the pair of pressure vessels 10 and 12 are rapidly rotated to bring the loaded pressure vessel within the confines of the compacting frame and to simultaneously remove the opposing pressure vessel from the compacting frame so that a compacted part can be removed therefrom. The vessels are then locked into position with a locking wedge 25 controlled by a ram 27. Rapid rotating of the two pressure vessels 10 and 12 about the common aix 16 is accomplished with a Geneva type gear mechanism which imparts a 180 reciprocating rotation to a drive gear 32 associated with the support frame 14 carrying the two pressure vessels l0 and 12. The drive gear 32 is driven by gear 34 which receives its driving moments from a gear 36 via gear 35. The gear 36- includes a slotted portion 38 for receiving a follower 40 carried by a driving arm 42. The driving arm 42 is reciprocated back and forth by known means which includes a hydraulic motor (see FIG. 7 and discussion relating thereto) for reciprocating the arm back and forth about an axis 44 for an angular rotation of 90. This 90 rotation imparts at 180 rotation to the main drive gear 32 through a selection of appropriate gear ratios between the gears 36, 35, 34, and 32.

FIG. 3 illustrates basic components making up the pressure vessel and compacting assemblies of the present invention. Each pressure vessel 10 and 12 comprises a generally cylindrical structure having a bore 50 formed through its center axis so as to define a compacting chamber therein. Separate closing means 52 and 54 are provided for closing top and bottom openings, respectively, of the bore 50 so as to provide a closed and sealed compacting chamber during a compacting operation.

In the embodiment illustrated in FIG. 3, a dry bag system is shown wherein a deformable mold means, consisting of an inner elastomeric bag 56 and an outer elastomeric bag 58, is suspended within the compacting chamber for receiving a quantity of powder material 60 to be compacted into a self-supporting form. The illustrated arrangement also includes a self-contained isostatic system, comprising, for example, a quantity of hydraulic fluid 62, sealed within the compacting chamber for applying a compacting force to the quantity of material 60 when the pressure vessel is closed and pressurized. A pressurizing means 64, in the form of a piston member fitted within a bore formed through the bottom closing means 54, operates through the bottom closing means 54 for pressurizing the self-contained isostatic system during a compacting operation. This is accomplished without the introduction of high pressure fluid into the pressure vessel from an external source during such pressurizing, and this arrangement eliminates any requirement for penetration of the walls of the pressure vessel or for a use of high pressure fittings through the pressure vessel or through its closing means 52 and 54.

It can be appreciated from a study of FIG. 3 that when the pressure vessel 10 is pressurized by a movement of the piston'member 64 upwardly, the isostatic system is pressurized to apply forces from all directions to the powder material 60 contained within the deformable mold means. In the case of an isostatic system which utilizes a liquid for imparting an isostatic force to the deformable mold means, a manifold means 66 is fitted around the deformable mold means to support the mold means when it is unpressurized and to provide for a delivery of liquid through a number of passages 68 to external surfaces of the main body of the mold means. Structures of this type are known per se and do not form a separate part of the present invention.

The piston member 64 is driven upwardly to apply a pressurizing force to the isostatic system within the chamber of the pressure vessel by a separate piston member 70 fitted within a chamber positioned within the base 21 of the compacting frame and carried by the lower plate means 20. The second piston member 70is driven upwardly by hydraulic force applied to its bottom face, and the second piston member 70 is of a larger'diameter than the piston member 64 so as to provide for a multiplication of force which will be applied to the fluid system contained within the compacting chamber. The combination of the larger piston member 70 with the small piston member 64 is known as an intensifier means and has been known in the art prior to the present invention. In, the FIG. 3 illustration, the larger diameter piston member 70 is shown with an extended portion 71 in its withdrawn position below the upper surface level of a support platform 72 provided on the pressure plate 20 of the compacting frame, and the extended portion 71 is moved upwardly in engagement with the smaller piston member 64 when the-pressure vessel is to be pressurized. The smaller piston member 64 is limited in its range of downward movement by an annular retainer ring 74. Downward movement of the piston member 64, to depressurize the compacting chamber, is encouraged by an application of fluid pressure through a conduit 76 which communicates with an annular pressure reactive surface 78 of the smaller diameter piston member 64.

Considering the features discussed so far, it can be seen that the deformable mold means can can be filled with a compactible material 60, after which the pressure vessel 10 is advanced into a compacting position between the parallel pressure plate means 18 and 20. This movement places the smaller diameter piston member 64 in direct alignment with an extended portion 71 of the larger diameter piston member 70 contained within the base of the compacting frame. The top of the pressure vessel is closed by a movement of the closing means 52 downwardly so as to advance a deformable plug means 80 into the open top of the deformable mold means and to close the upper end of the compacting chamber of the pressure vessel. Downward and upward movements of the closing'means 52 are provided with a relatively small hydraulic ram (not shown in FIG. 3) carried above the upper pressure plate means 18 in a housing 82 (see FIG. 1). A connecting rod 84 extends between the ram and the closing means 52 through a bore provided through the pressure plate means 18. The plug means 80 is secured to the closing means 52 with an adhesive or by any other suitable means. However, it is not necessary for the ram which actuates the closing means 52 to resist the very high pressures developed within the pressure vessel 10 during a compacting operation because a separate spacer plate means 86 is provided for insertion between the top surface of the closing means 52 and the bottom surface of the upper pressure plate means 18 after the pressure vessel is closed. Thus, all upwardly directed forces from the pressurized chamber of the pressure vessel will be imparted to the spacer plate means 86 and to the very rigid upper pressure plate means 18.

During a typical pressurizing of the chamber illustrated in FIG. 3, considerable forces will be directed upwardly and downwardly against the upper and lower closing means 52 and 54, respectively. The lower closing means 54 is secured to the base of the pressure vessel with a number of spring-loaded fasteners 55 which permit the lower closing means 54 to move downwardly against the support platform 72 without releasing high pressure sealing means 57 provided between the lower closing means 54 and the bore 50 of the pressure vessel. Upwardly directed forces are received by the upper pressure plate means 18, as discussed above, and downward forces are received by the lower pressure plate means 20 through the support platform 72. When the pressure vessel is pressurized to relatively high pressures (for example, to 40,000 psig or higher), there is a discernible deflection of the upper and lower pressure plate means 18 and 20 even though these plates are designed as very strong and rigid structures. This slight movement of the upper and lower plate means results from further slight movements of the upper and lower closing means 52 and 54 outwardly away from the compacting chamber, however, these movements are insufficient to result in an unsealing of the compacting chamber within the pressure vessel.

Turning now to another feature of the present invneiton there is provided a supporting means 90 which functions to suspend the deformable mold means within the compacting chamber of the pressure vessel so that the deformable mold means can follow the slight movement of the upper closing means 52 discussed above. This is an important feature because prior art arrangements have attempted to fix the position of a deformable mold means within a compacting chamber, and this has resulted in a tendency for the plug means of prior art arrangements to withdraw from the deformable mold means during a deflection of closing structures associated with the plug means, thereby permitting an extrusion or other unwanted stress characteristic to be applied to the compactible material contained within the deformable mold means. In contrast, the arrangement of the present invention allows the deformable mold means to follow any slight movement of its deformable plug 80 (upwardly in the FIG. 3 orientation) during a pressurizing operation so as to maintain predetermined relationships between the plug means and the deformable mold means. This is accomplished with the supporting means which includes an annular groove 92 about its upper end for permitting limited axial movement of the supporting means 90 relative to the upper end of the pressure vessel 10. The supporting means 90 is suspended within the bore 50 by two semicircular retaining ring elements 94, and each of these elements has a projecting portion which is received within the annular groove 92 of the supporting means 90. The supporting means 90 includes a small diameter bore for receiving the deformable mold means and its manifold sleeve 66, together with a larger diameter bore portion for receiving a locating ring means 96 from which the inner elastomeric bag 56 is suspended. The supporting means 90 is illustrated in FIG. 3 in a slightly upwardly displaced position, but the supporting means would normally be pressed downwardly by the closing means 52 at the time of closing the pressure vessel 10 for a compacting operation. During compacting, a slight deflection of the closing means 52 upwardly would be followed by the supporting means 90, thereby maintaining the deformable mold in a predetermined and precise relative position with its plug means 80.

By providing an opening through the top of the supporting means 90, it is possible to remove the plug 80 and to load and unload the deformable mold without removing the supporting means 90 from the pressure vesselv This is a particularly advantageous arrangement because it allows high pressure sealing means 91, associated with the supporting means 90, to remain in a working position during loading and unloading of the pressure vessel, thereby avoiding potential damage to the sealing means 91 by its movement past an edge of the opening of the pressure vessel. Thus, it is possible to rapidly open and close the pressure vessel without any damage to its high pressure seals.

The supporting means 90 illustrated in FIG. 3 serves an additional function of reducing the diameter of the compacting chamber to receive a given diameter of isostatic tooling. Large or smaller diameters for tooling can be provided by interchanging the supporting means 90 with one having a different sized main bore therethrough. If this additional function is not desired, the following characteristic discussed above can be provided by a supporting means which consists of the loeating ring means 96, or other supporting structure for the deformable mold means, arranged to follow slight movements of the closing means 52 and the plug 80 during a compacting operation.

FIG. 4, taken in conjunction with illustrations of FIG. 3, further explains the various components which are assembled together to form isostatic tooling used with the apparatus of the present invention.

In the FIG. 4 view, the quantity of compactible material is illustrated in the form of a finished compact 100 having a convex surface configuration 102 at one end thereof and a bore 104 formed through its center axis so as to pass completely through the compact and through the one end on which the convex surface configuration is formed. The finished compact 100 is a selfsupporting product which can be subjected to further handling and treating to produce a final product. The final product may be of the identical form and size as the illustrated compact 100 or it may constitute a new shape and size resulting from a subsequent forming operation applied to the intermediate compact form which is illustrated. The illustrated compact is symmetrical about its center axis, and the bore 104 is precisely positioned on the center axis.

A base member 106 of the illustrated tooling functions to support and position a core rod means 108 for defining the bore to be formed in the compact. The base member 106 constitutes a rigid, non-deformable structure which can be closely fitted within the internal diameter of the supporting means 90 (see FIG. 3) within which the isostatic tooling is to be placed. The entire isostatic tooling package is precisely centered within the chamber bore 50 by a centering sleeve 110 (FIG. 3) which is fitted around an external diameter of the supporting means 90, and which provides the further function of locking the sealing ring 91 in place to precompress the sealing ring and to prevent dislodgment during depressurization of the pressure vessel. These arrangements provide for a precisecentering of the base member 106 and the core rod 108 within the compacting chamber. The core rod means 108 may constitute an integral structure with the base member 106, formed from the same rigid material (such as steel), or may constitute a separate component which is secured to the base member 106.

The base member 106 supports a deformable mold means which is illustrated as including an inner elastomeric bag 56 and an outer elastomeric bag 58 to define an open-ended cavity for holding a quantity of powder material while the powder material is being formed into the illustrated self-supporting compact 100. The inner and outer elastomeric bags are assembled together so as to be in substantial face-to-face contact with one another, and this provides for a frictional engagement between the two bags which is sufficient to hold them together in the assembly. Each of the elastomeric bags includes an opening through its bottom wall portion for receiving the core rod means 108 therethrough. The assembled relationship is illustrated in FIG. 3 wherein it can be seen that the core rod means 108 completely closes the bottom of the deformable mold so that no powder material will escape from the deformable mold during a compacting operation. A reduced diameter portion 112 may be provided at a base level of the core rod means for receiving the base of the elastomeric bag 58 in a tight sealing engagement.

As also shown in FIG. 4, the base member 106 supports a manifold means 66 for distributing fluid to all external surfaces of the deformable mold means. The

manifold means 66 is of a significantly smaller external diameter than the diameter of the bore within which the isostatic tooling is positioned so as to provide for sufficient clearance for a free flow of a pressurizing medium all around the manifold means. The inside diameter and shape of the manifold means is designed to define the unpressurized condition of the deformable mold means.

The locating ring means 96 comprises a relatively rigid structure, formed from metal or other nondeformable material, for carrying the full weight of the isostatic tooling and its contents when the isostatic tooling is secured thereto and lowered into the chamber of the pressure vessel. Also, the locating ring means carries the load on the tooling resulting from an air differential established by the downward movement of piston 64 which draws a partial vacuum on the deformable mold means to cause it to expand to the shape of the manifold after compacting is completed.

The isostatic tooling which is illustrated in FIG. 4 is merely representative of one form of tooling which may be utilized with the pressure vessel apparatus of the present invention. This tooling does not form a separate part of the present invention and is described in greater detail in a commonly owned application entitled Tooling For Receiving And Supporting A Quantity Of Powder Material To Be Pressed Into A Selfsupporting Compact, filed on even date herewith in the name of Kenneth Baxendale.

FIG. 5 illustrates details of construction of the small diameter piston member 64 discussed above with reference to FIG. 3. As noted above, the small diameter piston member 64 functions to apply a compression force to an isostatic medium, such as a liquid 62, contained within the compacting chamber. Because of the relatively high pressures'which can be developed with the apparatus of this invention, a certain amount of liquid leakage occurs past the piston member 64 when the piston member is operating against a liquid medium. Accordingly, it is necessary to replenish any liquid lost through leakage, and this is accomplished with a replenisher means of the type illustrated in FIG. 5. A supply of replenishing oil, or other liquid, is carried within the support structure 14 so that the replenishing liquid can be delivered to either of the pressure vessels 10 or 12 carried by the support structure. Delivery isthrough conduits leading from a pressurized supply reservoir 111 (see FIG. 1) to the conduit 76 discussedabove with reference to FIG. 3. The supply reservoir 111 includes a quantity of liquid which is pressurized by a quantity of gas contained within the reservoir. Adjustment of pressure of the gas can be used to regulate the pressure at which the reservoir liquid flows through the conduit 76. This adjustment permits an adjustment of a pressure differential that can be established between inside and outside surfaces of the deformable mold during depressurization of the system. Such depressurization causes the mold to be drawn outwardly to conform to the interior shape of the manifold means 66 dis cussed above. From there the liquid is carried to a chamber within which the pressure reactivesurface 78 of the piston member 64 is fitted and is admitted to the interior of the piston member 64 through one or more ports 120. As shown in FIG. 5, a central chamber 121 is defined within the piston member 64 for receiving such a supply of liquid. The central chamber is closed at its bottom end by an end cap structure 122 and at its top end by an assembly that includes a cylindrical block 124 which functions as a valve. The cylindrical block 124 is secured to a center rod 126 which supports a spring means 128 for normally urging the cylindrical block to a downwardly directed position which seals the chamber within the piston member 64. Compression on the spring means 128 is adjusted by turning an adjustment nut 129 on the threaded end of the center rod 126 (access being available through removal of end cap 122). Thus, during normal pressurizing of the compacting chamber, there is no leakage of oil to or from the interior chamber provided within the piston member 64. However, during depressurizing of the pressure vessel, the piston member 64 is moved downwardly, and this movement creates a pressure differential between the interior of the piston member 64 and the liquid isostatic system contained within the compacting chamber of the pressure vessel. At a certain level of pressure differential, set to develop only when the liquid volume within the compacting chamber has been reduced by a known amount of leakage therefrom, the spring means 128 is overcome by the higher pressure within the piston member 64, and this displaces the cylindrical block 124 from its sealed position on the top surface of the piston member 64. This allows a replenishing of liquid from the interior of the piston member 64 into the compacting chamber as the piston member 64 iswithdrawn to a starting position for a subsequent pressurizing operation. The cylindrical block 124 may be provided with a pin 130 to prevent rotation thereof during adjustment of compression on the spring means 128 with the adjustment nut 129.

FIG. 6 illustrates a hydraulic control circuit for controlling pressurization and depressurization of the apparatus of the present invention. A motor 200 (which may comprise a 50 horsepower motor operating at 1,200 rpm) drives two separate pumps 202 and 204. The pump 202 is a fixed displacement vane type of pump (capable of delivering about 21 gallons per minute, for example) and the pump 204 is a fixed volume piston pump (capable of delivering up to 24 gallons per minute). During initial pressurization of the pressure vessel, both pumps function to supply hydraulic fluid to the cylinder in which the larger piston member 70 is carried so as to drive the larger piston. This movement (upwardly in the FIG. 6 view) is transmitted to the smaller piston member 64 which applies a force to the isostatic system, as discussed above. Delivery of hydraulic fluid from pump 202 is carried out through a conduit 206, through a solenoid operated valve 208, through conduit 210, past a check valve 212, and into a conduit 214 which is also receiving fluid delivery from the pump 204. The conduit 214 delivers fluid through a solenoid operated valve 216 (when the valve is moved to the left from the position shown in FIG. 6) and into a delivery conduit 218 which drives the piston members 70 and 64 into the pressure vessel (in the direction of the arrow).

After initial pressurization and when the pressure level within the delivery system reaches about 2,000 psig, a relief valve 220 is opened (in response to a detection of 2,000 psig in pilot line 221) so that all fluid delivery from the pump 202 will be carried back to the reservoir 222. This dumping action reduces the volume of fluid delivery to the piston 70 during the final portion of its pressurizing stroke, and the pump 204 continues in its delivery of fluid until a preferred peak level (for example, about 2,800 psig) is reached. At this level, a relief valve 224 provides for sufficient recirculation of fluid back to tank to maintain the preferred peak level. The relief valve 224 is adjusted by one of three vent controls 226, 228, or 230, as selected by operation of a solenoid valve 232. When the solenoid valve 230 is in the position illustrated in FIG. 6, vent control 228 functions to control relief valve 224 to operate at the preferred peak pressure level. A pressure switch 234 senses the peak pressure level and actuates a circuit to initiate a dwell period after which a solenoid associated with valve 232 is energized to shift the valve 232 and to place the vent control 230 in circuit. This initiates a decompression cycle which includes an initial phase during which fluid from the main delivery conduit 214 is throttled back to tank until a reduced pressure (for example, about 1,000 psig) level is reached. At that point, the solenoid valve 216 is shifted (with a timing mechanism which calculates the approximate time for arriving at the reduced pressure level) to a position (as shown in FIG. 6) to permit a rapid dumping of hydraulic fluid from the cylinder in which the piston member is carried and to apply a positive pressure within a chamber 238 which allows the com bined piston members 70 and 64 to be rapidly withdrawn from the pressure vessel. When the piston members 70 and 64 are fully withdrawn from the pressure vessel, a limit switch (not shown) is actuated to shift the valve 232 to place vent control 226 in circuit, thereby permitting a full flow of fluid from the relief valve 224 back to tank. This reduces the operating level of the relief valve 224 down to a minimal amount of about 50 psig. This provides for a reduction of pressure within the entire system to prevent unnecessary restriction of flow and overheating of the fluid within the system, and conserves power, during idling of the system between compacting operations.

After the piston member 70 and 64 are fully withdrawn, and after the vessel has been unsealed and opened, the solenoid valve 208 is energized to direct the flow of fluid from pump 202 to a conduit 240 leading to a hydraulic motor associated with the driving means for the pressure vessels discussed with reference to FIGS. 1 and 2 above. The control circuit for this driving means is shown in FIG. 7 where the conduit 240 is continued from the circuit illustrated in FIG. 6.

Referring to FIG. 7, rotation of the two pressure vessels is carried out with a known type of hydraulic motor 300 which provides for a rotary actuation of a pair of opposed vanes 302 within separate chambers 304. The chambers 304 are defined by fixed structures 306 contained within the hydraulic motor. By delivering a fluid to one side or the other of the vanes 302, the actuator is caused to rotate in either a clockwise or counterclockwise direction, and this rotation is imparted to an outputshaft 308 connected to the drive arm means 42 discussed with reference to FIG. 2.

Control of rotation of the hydraulic motor 300 in either a clockwise or counterclockwise direction is effected with a solenoid operated valve 310. Movement of the valve towards the right in the FIG. 7 view delivers high pressure fluid from the conduit 240 through a conduit 312 which pressurizes the chambers 304 in the areas in which have been stippled in the FIG. 7 view. This results in a clockwise rotation of the vanes 302. Movement of the solenoid control valve 310 towards the left in the FIG. 7 view results in a delivery of pressurized fluid (about l,200 psig) through a separate conduit 314 which delivers fluid to the portions of the chambers 304 which are not stippled in the FIG. 7 view, and this results in a counterclockwise rotation of the vanes 302. In either direction of movement, high pressure fluid enters the motor by way of one of the circuits in which check valves 315 are included.

The hydraulic motor 300 is capable of rotating the two pressure vessels illustrated in FIGS. 1 and 2 for 180 in a time period of about 1 second. This rapid rotation is achieved by initially delivering high pressure fluid at about 1,200 psig to the hydraulic motor 300 to rapidly accelerate the motor in one direction or the other. About halfway through such rotation, it is necessary to start braking the movement of the motor since the rapid movement of the pressure vessels will tend to rotate the motor if a braking force is not applied. Braking is controlled with a relief valve 316 having high and low pressure levels of operation. At the halfway point of rotation, a limit switch is contacted and the relief valve 316 is shifted to a lower pressure condition by an operation of a solenoid operated valve 318. When the solenoid operated valve 318 is in the position shown in FIG. 7, a low pressure condition is established in the main delivery line 240, thereby reducing the pressure at fluid flow to the chamber portion 304 being pressurized. At the same time, fluid is being exhausted from the portions of the chambers 304 which are unpressurized, and during this final half of rotation this exhausting takes place through one of the restrictor valves 320 which tends to decelerate the rotational movement of the vanes 302. During the first half of rotation, the high pressure delivery of fluid establishes a mode of operation for one of the relief valves 322 to allow rapid dumping of fluid from the unpressurized parts of the motor back to tank. When the solenoid valve 318 is shifted to lower pressure in the main delivery line 240, the valves 322 shift to a mode which prevents fluid delivery therethrough and which forces the fluid through one of the restrictor valves 320.

Having described a specific embodiment of the present invention, it can be appreciated that certain changes in design can offer the full equivalent of the structures and functions which have been discussed above. All such equivalent changes are intended to be included within the scope of protection defined in the claims which follow.

What is claimed is:

l. A high production rate apparatus for applying a relatively uniformly distributed pressure to a quantity of compactible material placed in a chamber defined within a pressure vessel, comprising a pressure vessel having a chamber defined therein,

a deformable mold means which can be suspended within the chamber of said pressure vessel a self-contained isostatic system carried within said pressure vessel for applying a compacting force to a quantity of material placed within said deformable mold means,

closing means for closing said chamber during a compacting operation,

pressurizing means operating through said closing means for pressurizing and depressurizing said isostatic system during a compacting operation without the introduction of high pressure fluid into the pressure vessel from an external source during such pressurizing, said pressurizing means comprising (a) a first piston means which can be advanced into said chamber to apply a pressurizing force to said fluid carried within the chamber, and (b) a second piston means for multiplying the force applied to said fluid by the first piston means, and

a hydraulic control system operated externally of said pressure vessel for controlling the movements of said first and second piston means.

2. The apparatus of claim 1 wherein said isostatic system includes a quantity of fluid carried within said chamber so as to contact outside surfaces of said deformable mold means during a pressurizing of the deformable mold means.

3. The improvement of claim 1 wherein said chamber of said pressure vessel is defined by a bore extending completely through the pressure vessel to thereby provide oppositely directed openings extending along the axis of said bore, and wherein said closing means comprises separate closing means for each end of said bore.

4. The improvement of claim 3, and including a compacting frame for receiving said pressure vessel during a compacting operation, said compacting frame having a pair of spaced-apart pressure plate means which are secured in fixed positions for receiving the pressure vessel therebetween for locking said closing means of the pressure vessel during a compacting operation.

5. The improvement of claim 4, and including moving means for advancing said pressure vessel into and out of a position between said pressure plate means.

6. The improvement of claim 4, and including a spacer plate means which can be inserted between one end of said pressure vessel and one of said pressure plate means to substantially fill a clearance space provided between said pressure vessel and said one pressure plate means.

7. The improvement of claim 4 and including a second pressure vessel of the same design as said firstnamed pressure vessel, said two pressure vessels being carried at opposite ends of a support structure so that the two pressure vessels can be rotated about a common axis to provide for alternating placement of each vessel between said pair of pressure plate means.

8. An apparatus for containing a quantity of material to be compacted by the force of a pressurized fluid, said apparatus being of a type which includes a cylindrical pressure vessel having a bore extending therethrough with the center axis of the bore being coincident with the center axis of the pressure vessel, a deformable mold carried within said bore for receiving a quantity of material to be compacted, a first closing means for closing one end of said bore of said pressure vessel, a second closing means for closing a second end of said bore of said pressure vessel, a pair of spaced apart pressure plates for receiving said pressure vessel therebetween during a compacting operation, and moving means for advancing the pressurevessel to a position between said pair of spaced apart pressure plates, the improvement comprising an essentially self-contained isostatic system carried within the bore of said pressure vessel, and pressurizing means operating through one of said closing means for imparting a pressure to said isostatic system contained within said pressure vessel so as to (a) expand said first and second closing means outwardly in opposite directions against respective pressure plate means, thereby forming a tightly sealed relationship between the pressure vessel and said pressure plate means while maintaining a sealed relationship between said closing means and the pressure vessel, and to (b) impart a relatively high isostatic force against material contained within said deformable mold, said pressuring means comprising a piston means fitted within a bore formed through one of said closing means, and including actuating means carried externally of said pressure vessel for multiplying force on said piston means, said actuating means being separable from said piston means during depressurization of said isostatic system so that the piston means can separate from the actuating means when said pressure vessel is moved out of its operating position between said pressure plates.

9. The improvement of claim 8 wherein said pressurizing means includes an intensifier means for multiplying the pressure on said isostatic system in said chamber, and including replenisher means in combination with said intensifier means for automatically supplying additional fluid to said chamber in response to a loss of fluid from the chamber through leakage.

10. The improvement of claim 9 wherein said intensifier means is operated from a hydraulic control circuit carried externally of said pressure vessel.

11. The improvement of claim 10 wherein said hydraulic control circuit includes control means for depressurizing said chamber through a reverse operation of said intensifier means.

12. The apparatus of claim 8 wherein said pressure vessel can be moved between (a) said position between said pair of spaced apart pressure plate means and (b) a position away from said pressure plate means where said pressure vessel can be loaded and unloaded, and including loading means for placing said quantity of material into said deformable mold in said pressure vessel, and

unloading means for removing the material from said chamber after being compacted.

13. In apparatus for compacting a powder material by applying a force to the material while the material is carried in a deformable mold means suspended within a chamber defined in a pressure vessel, the improvement in said deformable mold means and said pressure vessel comprising high pressure sealing means associated with said supporting means for sealing the opening of said chamber when said closing means is moved to a position for closing the chamber, said sealing means being arranged to remain in a working position during opening and closing movements of said closing means.

14. The apparatus of claim 13 and including an improved means for applying a force to material in said deformable mold means comprising an isostatic system carried within said pressure vessel,

pressurizing means operating through a closing means for pressurizing the isostatic system carried within said pressure vessel, said pressurizing means being in the form of a piston means which can be advanced through a bore formed through said pressure vessel so as to apply a compression force to said isostatic system without the introduction of high pressure fluid into the pressure vessel from an external source.

15. The apparatus of claim 14 wherein said piston means of said pressurizing means is actuated by a second piston means having a larger diameter than said first-named piston means so as to multiply the force applied to said isostatic system, and wherein said second piston means is fitted within a chamber carried by a compacting frame structure, and said first-named piston means is carried within said pressure vessel so that the pressure vessel can be moved relative to said compacting frame structure.

16. The apparatus of claim 13 wherein said supporting means comprises an annular sleeve structure which can be suspended within a bore defined in said pressure vessel for receiving and supporting said deformable mold means, said annular sleeve structure being open at one end to allow passage of a plug means therethrough.

17. The apparatus of claim 13 and including a hydraulic control circuit having means for controlling a depressurizing of said pressure vessel, said means for controlling depressurizing including means for establishing an initial relatively slow rate of decompression followed by a relatively more rapid rate of decompression.

18. The apparatus of claim 14 wherein said piston means includes a replenishing means for automatically supplying a metered volume of fluid into said pressure vessel upon withdrawal of the piston means from the pressure vessel.

19. The apparatus of claim 1 wherein said first piston means includes a replenishing means for automatically supplying a metered volume of fluid into said pressure vessel upon withdrawal of said first piston from the pressure vessel.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,830,607 Dated August 2 1914 Kenneth C. Baxendale, et al Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shownbelow:

Column 1, line 32, change "mterial" to --material-} line 34, change "copaction" to -compaction--. Column 3, 1i'ne62, change "on" to --one--. Column 4, line 23, change "eleastomeric" to --elastomeric--. Column 5, line 22, change "postion" to ----position---;

line 24, after suchadd --as a ferrous metal powder,

is accomplished with--; line 26, change "provide" to --provided--. Column 7, lines 65 & 66, change "invn'ei-ton to -inven-tion--.

Signed and sealed this 29th day of October 1974.

(SEAL) Attest McCOY M. GIBSON JR. C. vMARSHALL DANN Attesting Officer Commissioner of Patents 

1. A high production rate apparatus for applying a relatively uniformly distributed pressure to a quantity of compactible material placed in a chamber defined within a pressure vessel, comprising a pressure vessel having a chamber defined therein, a deformable mold means which can be suspended within the chamber of said pressure vessel a self-contained isostatic system carried within said pressure vessel for applying a compacting force to a quantity of material placed within said deformable mold means, closing means for closing said chamber during a compacting operation, pressurizing means operating through said closing means for pressurizing and depressurizing said isostatic system during a compacting operation without the introduction of high pressure fluid into the pressure vessel from an external source during such pressurizing, said pressurizing means comprising (a) a first piston means which can be advanced into said chamber to apply a pressurizing force to said fluid carried within the chamber, and (b) a second piston means for multiplying the force applied to said fluid by the first piston means, and a hydraulic control system operated externally of said pressure vessel for controlling the movements of said first and second piston means.
 2. The apparatus of claim 1 wherein said isostatic system includes a quantity of fluid carried within said chamber so as to contact outside surfaces of said deformable mold means during a pressurizing of the deformable mold means.
 3. The improvement of claim 1 wherein said chamber of said pressure vessel is defined by a bore extending completely through the pressure vessel to thereby provide oppositely directed openings extending along the axis of said bore, and wherein said closing means comprises separate closing means for each end of said bore.
 4. The improvement of claim 3, and including a compacting frame for receiving said pressure vessel during a compacting operation, said compacting frame having a pair of spaced-apart pressure plate means which are secured in fixed positions for receiving the pressure vessel therebetween for locking said closing means of the pressure vessel during a compacting operation.
 5. The improvement of claim 4, and including moving means for advancing said pressure vessel into and out of a position between said pressure plate means.
 6. The improvement of claim 4, and including a spacer plate means which can be inserted between one end of said pressure vessel and one of said pressure plate means to substantially fill a clearance space provided between said pressure vessel and said one pressure plate means.
 7. The improvement of claim 4 and including a second pressure vessel of the same design as said first-named pressure vessel, said two pressure vessels being carried at opposite ends of a support structure so that the two pressure vessels can be rotated about a common axis to provide for alternating placement of each vessel between said pair of pressure plate means.
 8. An apparatus for containing a quantity of material to be compacted by the force of a pressurized fluid, said apparatus being of a type which includes a cylindrical pressure vessel having a bore extending therethrough with the center axis of the bore being coincident with the center axis of the pressure vessel, a deformable mold carried within said bore for receiving a quantity of material to be compacted, a first closing means for closing one end of said bore of said pressure vessel, a second closing means for closing a second end of said bore of said pressure vessel, a pair of spaced apart pressure plates for receiving said pressure vessel therebetween during a compacting operation, and moving means for advancing the pressure vessel to a position between said pair of spaced apart pressure plates, the improvement comprising an essentially self-contained isostatic system carried within the bore of said pressure vessel, and pressurizing means operating through one of said closing means for imparting a pressure to said isostatic system contained within said pressure vessel so as to (a) expand said first and second closing means outwardly in opposite directions against respective pressure plate means, thereby forming a tightly sealed relationship between the pressure vessel and said pressure plate means while maintaining a sealed relationship between said closing means and the pressure vessel, and to (b) impart a relatively high isostatic force against material contained within said deformable mold, said pressuring means comprising a piston means fitted within a bore formed through one of said closing means, and including actuating means carried externally of said pressure vessel for multiplying force on said piston means, said actuating means being separable from said piston means during depressurization of said isostatic system so that the piston means can separate from the actuating means when said pressure vessel is moved out of its operating position between said pressure plates.
 9. The improvement of claim 8 wherein said pressurizing means includes an intensifier means for multiplying the pressure on said isostatic system in said chamber, and including replenisher means in combination with said intensifier means for automatically supplying additional fluid to said chamber in response to a loss of fluid from the chamber through leakage.
 10. The improvement of claim 9 wherein said intensifier means is operated from a hydraulic control circuit carried externally of said pressure vessel.
 11. The improvement of claim 10 wherein said hydraulic control circuit includes control means for depressurizing said chamber through a reverse operation of said intensifier means.
 12. The apparatus of claim 8 wherein said pressurE vessel can be moved between (a) said position between said pair of spaced apart pressure plate means and (b) a position away from said pressure plate means where said pressure vessel can be loaded and unloaded, and including loading means for placing said quantity of material into said deformable mold in said pressure vessel, and unloading means for removing the material from said chamber after being compacted.
 13. In apparatus for compacting a powder material by applying a force to the material while the material is carried in a deformable mold means suspended within a chamber defined in a pressure vessel, the improvement in said deformable mold means and said pressure vessel comprising closing means for closing and sealing an opening in said chamber, and supporting means for suspending said deformable mold means in said chamber so that the deformable mold means can follow limited movement of said closing means away from said chamber when pressure conditions are increased in the chamber, and high pressure sealing means associated with said supporting means for sealing the opening of said chamber when said closing means is moved to a position for closing the chamber, said sealing means being arranged to remain in a working position during opening and closing movements of said closing means.
 14. The apparatus of claim 13 and including an improved means for applying a force to material in said deformable mold means comprising an isostatic system carried within said pressure vessel, pressurizing means operating through a closing means for pressurizing the isostatic system carried within said pressure vessel, said pressurizing means being in the form of a piston means which can be advanced through a bore formed through said pressure vessel so as to apply a compression force to said isostatic system without the introduction of high pressure fluid into the pressure vessel from an external source.
 15. The apparatus of claim 14 wherein said piston means of said pressurizing means is actuated by a second piston means having a larger diameter than said first-named piston means so as to multiply the force applied to said isostatic system, and wherein said second piston means is fitted within a chamber carried by a compacting frame structure, and said first-named piston means is carried within said pressure vessel so that the pressure vessel can be moved relative to said compacting frame structure.
 16. The apparatus of claim 13 wherein said supporting means comprises an annular sleeve structure which can be suspended within a bore defined in said pressure vessel for receiving and supporting said deformable mold means, said annular sleeve structure being open at one end to allow passage of a plug means therethrough.
 17. The apparatus of claim 13 and including a hydraulic control circuit having means for controlling a depressurizing of said pressure vessel, said means for controlling depressurizing including means for establishing an initial relatively slow rate of decompression followed by a relatively more rapid rate of decompression.
 18. The apparatus of claim 14 wherein said piston means includes a replenishing means for automatically supplying a metered volume of fluid into said pressure vessel upon withdrawal of the piston means from the pressure vessel.
 19. The apparatus of claim 1 wherein said first piston means includes a replenishing means for automatically supplying a metered volume of fluid into said pressure vessel upon withdrawal of said first piston from the pressure vessel. 